Microsoft may be ready to go hostile in its bid for Yahoo as soon as today, according to a report Thursday night in The Wall Street Journal.

Citing unnamed people familiar with the matter, The Journal reported the situation was fluid and that the company could change its strategy. Microsoft would not comment.

Chief Executive Steve Ballmer told The Journal earlier Thursday he can build an Internet ad business without buying Yahoo.

Meanwhile, Yahoo is exploring an ad partnership with Google. Impressed by a two-week test finished last month, Yahoo could firm up a long-term deal within a week, The Journal said.

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